Small thump when shifting

I've noticed that there seems to be a small "thump" sound when shifting from 1st to 2nd gear (but not any other gears). The thump seems to be coming from in front of me, somewhere in the engine bay. It's not a loud sound - in fact if you weren't paying attention you probably wouldn't notice it.

 

For all I know it could've been there since day 1 and I might just be noticing it now (got about 2300 miles on it). Any ideas? Something I should be worried about?

is it the actual shift that makes the bump, or clutch action or engaement of power?

That would be clutch action I think... I hear the thump the moment I depress the clutch in fully while in 1st gear

Trunk monkey rolling around?

Isn't it the result of the rear end making noise? I believ ethere's a bushing kit for ~30 dollars that is supposed to fix that. When I was new to Subaru AWD cars I got that a lot, but you learn to drive so that you don't get it after a while.

Update: after paying more attention I've noticed the thump also occurs in other shifts, but just not as noticeable as the 1st -> 2nd gear shift. It happens under acceleration when shifting, and if I depress the clutch somewhat quickly.

 

If I depress the clutch a tad slower I usually don't get the thump. And subconciously I think my driving style is changing/adjusting to that (ie depressing the clutch slower now).

Get it checked by dealer. Any kind of thumping could mean something's binding amongst all the differentials and joints.

ive heard it too...i think its just the crappy mounts

or just easy off on the clutch?

SOME ONE ELSE HAS IT!! I got this on my legacy after my clutch change and it's gotten really loud. I can hear it over music. It sounds like something banging into the firewall. Subaru gets it tomorrow so i'll see what they find out.

It may not be related but it doesn't hurt to check the bolts for the front crossmember support. All but 3 of the bolts were finger tight and caused a pop/thunk when accelerating/decelerating and even when turning.

 

http://www.mustangmods.com/data/3665/crossmember.jpg

SOME ONE ELSE HAS IT!! I got this on my legacy after my clutch change and it's gotten really loud. I can hear it over music. It sounds like something banging into the firewall. Subaru gets it tomorrow so i'll see what they find out.

 

I noticed the thump last night. In my car it is very low in volume and hard to notice.

Could be this, from Unabomber's Shifting FAQ at http://forums.nasioc.com/forums/sho...threadid=587096 :

 

When I shift from 1st to 2nd, there is a thump sound coming from the rear end of the car. What causes this? The thump is the rear differential hitting either the cross member or the bottom of your car. This is caused by driveline shock due to aggressive driving and shifting. This type of driveline shock is a direct result of maximum acceleration. A thump from the rear end can occur with any shift, but most commonly occurs during the 1-2 shift due to it having the greatest internal transmission speed differential between first and second gear.

 

How to I remove the thump sound? Many people have experienced a reduction in rear differential noise by the installation of stiffer STi transmission mounts and/or differential mounts. The wisdom of this method is highly debated though. Common sense thought processes indicate that the stiffer mounts only transfer the shock to internal transmission and differential components. The ultimate cure is to modify the shifting technique where the driveline shock occurs.

 

How do I shift without the thump? You should wait until the point where you are no longer pressed into the back of your seat to let the clutch out on your second gear shift. As to the actual application of this technique:

 

1. You are in first gear, taking it to your favorite shift RPM.

2. Once you reach this RPM, let off the gas pedal and depress the clutch.

3. Shift into second. (Items 2 & 3 can be done quickly)

4. "The wait". Judge it based on your body's movement. Visualize your pelvis as the axis....when the rearward pressure of acceleration leaves your body and you feel as if you can naturally lean forward at the waist.....this is the shift point.

5. Release the clutch.

 

This is a shifting technique that requires some practice due to variances from car to car. Yes, it's slower, but better for your rear differential and transmission in the long run.

 

Plus, read the whole shifting FAQ for some really good info.

i get the thump, but i believe mine is due to the perrin dp i have installed sin cei haven't manufactured any brackets to secure it yet.

My thump happens while stopped (car not moving at all) and first shifting into 1st. So I don't think Unabomber's Shifting FAQ has the answer for me at least.

My thump happens while stopped (car not moving at all) and first shifting into 1st. So I don't think Unabomber's Shifting FAQ has the answer for me at least.

Have you checked the torque of the transmission crossmember bolts? I'm going to check ALL the bolts under my car this weekend after thinking more about the bolts being really loose on the front crossmember support on my car...

I checked the bolts but after subaru had their way with it the noise got louder and is now accompanied by another noise that sounds almost like a piece of metal bending under tension. None of the bolts are loose and i've taken everything off and put it back on again. This is going to drive me mad. What about those times i don't want to blast music in the car?